Continuous casting of an ingot has been conventionally performed by injecting metal melted by vacuum arc melting and electron beam melting into a bottomless mold and withdrawing the molten metal downward while being solidified.
Patent Document 1 discloses an automatic control method for plasma melting casting, in which titanium or a titanium alloy is melted by plasma arc melting in an inert gas atmosphere and injected into a mold for solidification. Performing plasma arc melting in an inert gas atmosphere, unlike electron beam melting in vacuum, allows casting of not only pure titanium, but also a titanium alloy.